Antivasospastic Effects of Hydroxyfasudil, a Rho-Kinase Inhibitor, After Subarachnoid Hemorrhage

We investigated the anti-vasospastic potential of fasudil's active metabolite, hydroxyfasudil, a Rho-kinase inhibitor, after subarachnoid hemorrhage (SAH) and also its effect on hemorheological abnormalities following cerebral ischemia. Chronic cerebral vasospasm was produced using a two-hemorrhage canine model. On day 7, angiographic vasospasm was observed in all animals, and intravenous administration of hydroxyfasudil (3 mg·kg^-1·30 min^-1) significantly reversed the vasospasm (predose diameter of the basilar artery, 57.9% ± 2.0% of the baseline before the injection of blood; postdose diameter, 64.5% ± 1.9%). The viscosity of whole blood was significantly increased 24 h after 1 h middle cerebral artery occlusion in rats. Hydroxyfasudil (3 and 10 mg/kg, i.p.) significantly decreased blood viscosity. The specificity of hydroxyfasudil was examined against a panel of 17 protein kinases using ELISA analysis. Hydroxyfasudil inhibited Rho-kinase α and β at a concentration of 10 μM by 97.6% and 97.7%, respectively. No other protein kinase was inhibited with 10 μM hydroxyfasudil by over 40%. The present results indicate hydroxyfasudil is a selective inhibitor of Rho-kinase. The results also suggest that hydroxyfasudil contributes to the potency of fasudil to prevent cerebral vasospasm and hyperviscosity and suggest the potential utility of hydroxyfasudil as a therapeutic agent for patients with SAH.